Combustion characteristics of liquid fuel diffusion flame at capillary oulet

In order to study the characteristics of micro scale diffusion flame, liquid fuels were chosen for combustion experiment, and the theoretical models were used to estimate the height of the laminar flame. The following results were obtained. The flame size increased with the increase of the volume flow; in the horizontal direction, when the fuel volume flow was more than 50μL/min, a droplet injection occurred because of the incomplete fuel evaporation, and the flame size changed a little; when the capillary was placed vertically, because of the greater influence of buoyancy, the flame height was elongated. Flame oscillation period decreased with the increase of volume flow, and the bigger flame size meant the stronger flame oscillation. Flame oscillation period in vertical direction was smaller than in horizontal direction. With the increase of carbon content, the flame size became larger, and the oscillation was stronger. Kerosene with more carbon content injected fuel around the nozzle, resulting in unstable flame. The flame height was proportional to the Reynolds number of the fuel vapor at nozzle in the vertical direction, Roper model predicted the experimental result best, helping to calculate the laminar diffusion flame height of liquid hydrocarbon fuels in the vertical direction.